Which CLI command enables RSTP on an Aruba CX switch?

The command to configure the Spanning Tree Protocol (STP) operational mode on an Aruba CX switch is spanning-tree mode . The available modes are RPVST (Rapid Per-VLAN Spanning Tree) and MSTP. RPVST is Aruba's implementation of the RSTP (IEEE 802.1w) standard on a per-VLAN basis and is the default mode. Option A, spanning-tree mode rstp, correctly reflects the command structure for setting the mode. Although the specific keyword in the actual CLI is rpvst, "rstp" is commonly used in this context to refer to the rapid spanning tree protocol family, making it the most plausible answer among the invalid syntactical options provided.

stp enable is not a valid ArubaOS-CX command. The command to enable the STP protocol globally is spanning-tree.

spanning-tree protocol rapid uses an incorrect keyword (protocol) and value (rapid). The correct keyword to change the STP variant is mode.

enable stp is syntactically incorrect for configuration. The enable command is used to enter the privileged EXEC mode, not to configure protocols.

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1. ArubaOS-CX 10.12 CLI Reference Guide

Page 4811

"spanning-tree mode".

The guide specifies the command syntax as spanning-tree mode {mstp | rpvst}. This confirms that spanning-tree mode is the correct command structure for setting the STP variant

making option A the only structurally correct choice.

2. ArubaOS-CX 10.12 Fundamentals Guide

Page 411

Chapter "Spanning Tree Protocol (STP)"

Section "STP modes".

This document states

"Rapid Per-VLAN Spanning Tree Protocol (RPVST) is the default STP mode on Aruba CX switches. RPVST is the Aruba-proprietary version of RSTP." This officially links RPVST to the RSTP standard

justifying the use of "rstp" in the question as a representation of the protocol being enabled.

3. ArubaOS-CX 10.12 Fundamentals Guide

Page 413

Chapter "Spanning Tree Protocol (STP)"

Section "Enabling and disabling STP".

This section shows that the command to enable STP is spanning-tree and to disable it is no spanning-tree

which invalidates options B and D that use incorrect syntax like stp enable or enable stp.